Women (and sometimes men) typically wear hosiery (nylons, tights, leggings) on their legs, usually under a dress or skirt. Reasons people wear hosiery are: for support, to even skin tone and flatter the body, for additional warmth, to cover their legs to be more conservative, as an undergarment, for extra coverage in case her dress/skirt flies up, or simply as a fashion accessory.
Typical hosiery is made largely of spun nylon blended with spandex, sometimes with a cotton-lined crotch. The top of the garment is folded over, creating a waistband at the top of the garment. The waistband is deemed necessary in order to finish the knit nylon, as well as being necessary in order to prevent the garment from slipping down from the waist to the wearer's hips. As those skilled in the art will understand, a variety of other yarns are used or blended to make the legs.
Traditionally, whether hosiery is control top or designed for comfort, the waistband digs into the wearer's body. The digging effect is uncomfortable for the wearer, as her body is constricted. The discomfort is further exacerbated when the wearer is seated and/or after a full day dressed in traditional hosiery. In addition to discomfort, traditional waistbands are inadequate because they create an undesirable look where the woman's body bulges over the top of the narrow, constricting waistband.